University of Münster
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- A “fresh” R installation already contains hundreds of functions.
- Functions are organized in libraries.
- Libraries address a certain topic or area (e.g., graphics, a specific statstical method)
- A package is a ‘container’ for distributing and sharing libraries.
- You can add additional packages to extend you R installation.
- Additional packages are provided in repositories or in seperate files.
- Repositories are online data storages.
- The most important repository for R is CRAN
(The Comprehensive R Archive Network)
- You find a list of all CRAN packages on
https://cran.r-project.org/Packages
- You get an overview of all functions within a package with the
help()or short?function.- You can directly install a package from CRAN with the
install.packages()function.
After successful installation, add on packages have to be activated and loaded into memory in each R sesssion with the library() function.
Note: You only install once, but you use library() each time you restart R or R Studio.
Install the packages psych and tidyverse.
Activate both packages with
library(tidyverse)
library(psych)
As soon as you have more tham one source file and/or external data, it makes sense to start a project instead of just using single source files.
The place on your harddrive R will save and load data from by default (i.e. when no other place is explicitly set). Use the getwd() and setwd() functions to get and set the working directory.
You can start a project from R studio through:
read_excel() function from the readxl package (included in tidyverse) is used to import files created by Microsoft Excel.library(readxl)
dat <- read_xlsx("cars.xlsx")
names(dat) # this function shows the variable names of a data frame [1] "mpg" "cyl" "disp" "hp" "drat" "wt" "qsec" "vs" "am" "gear"
[11] "carb"
| mpg | cyl | disp | hp | drat | wt | qsec | vs | am | gear | carb |
|---|---|---|---|---|---|---|---|---|---|---|
| 21.0 | 6 | 160 | 110 | 3.90 | 2.620 | 16.46 | 0 | 1 | 4 | 4 |
| 21.0 | 6 | 160 | 110 | 3.90 | 2.875 | 17.02 | 0 | 1 | 4 | 4 |
| 22.8 | 4 | 108 | 93 | 3.85 | 2.320 | 18.61 | 1 | 1 | 4 | 1 |
dat.View() function to see the dataset.Note: View() opens a new tab in RStudio with the content of a data frame (e.g. View(dat)).
mpg (miles per gallon) for cars with 4, 6, and 8 cylinders (variable cly).mpg (miles per gallon) for cars with 4, 6, and 8 cylinders (variable cly).[1] 26.66364
[1] 19.74286
[1] 15.1
Jürgen Wilbert - Introduction to R